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Optical Detection Techniques: Course Notes Overview by DiMarzio & McKnight

This course resource, developed by Professors Charles A. DiMarzio and Stephen W. McKnight at Northeastern University, delves into the principles of optical detection. It covers essential topics including sources, radiometry, noise issues, detector physics, signal statistics, and detection techniques across various electromagnetic spectrum regions. The goal is to extract meaningful data from light variations in space and time, enabling practical applications in computer systems. The notes provide insights into challenges like noise management and detector performance, essential for students and professionals in optical engineering.

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Optical Detection Techniques: Course Notes Overview by DiMarzio & McKnight

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  1. ECEG287 Optical Detection Course NotesPart 19: Conclusion Profs. Charles A. DiMarzio and Stephen W. McKnight Northeastern University, Spring 2004 DiMarzio & McKnight, Northeastern University

  2. VIS= 0.40-0.75μ γ-Ray RF Electromagnetic Spectrum (by λ) UV= Near-UV: 0.3-.4 μ Vacuum-UV: 100-300 nm Extreme-UV: 1-100 nm IR= Near: 0.75-2.5μ Mid: 2.5-30μ Far: 30-1000μ 10 nm =100Å 0.1 μ 1 μ 10 μ 100 μ = 0.1mm (300 THz) 0.1 Å 1 Å 10 Å 1 mm 1 cm 0.1 m X-Ray Soft X-Ray Mm-waves Microwaves DiMarzio & McKnight, Northeastern University

  3. What is Optical Detection? • The goal is to get information from light. • Usually we look for variations in the amount of light over • space... • or time... • or spectrum... • or some combination of these. • Generally the output is an electrical signal. • It may be digitized for use in a computer. • We need to measure this signal in the presence of noise. DiMarzio & McKnight, Northeastern University

  4. Course Overview 2. Sources and Radiometry 3. Noise 2-5. Detectors 6. Circuits 7. Coherent Detection 8. Signal Statistics 9. Array Detectors DiMarzio & McKnight, Northeastern University

  5. Some Detection Issues • Optics • Radiometry, Beam Shaping, and Filters • Detector Physics • Converting Optical Energy to Electrical • Receiver Circuit • Matching to Detector, Proper Biasing • Interpretation of Data • Dealing with Noise and Signal Statistics DiMarzio & McKnight, Northeastern University

  6. Spectral Response Modulation Response Responsivity Noise (NEP) Damage Level Sensitive Area Circuit Considerations Device-Specific Issues Filtering Angle, Position, Wavelength Packaging Window Transmission, Position Power Requirements Cooling/Vacuum Requirements General Detector Issues DiMarzio & McKnight, Northeastern University

  7. Square-Law Detector DiMarzio & McKnight, Northeastern University

  8. Noise Signal + Noise Ps Ps Pn DiMarzio & McKnight, Northeastern University

  9. Noise Issues • Optical Signal Power (Watts) • Normally Related to Some Desired Quantity (Reflectivity, Temperature, Distance, Magnetic Field, Scattering, Absorption, etc.) • NEP (Watts per root Hertz) • Can be Related to “NEX” • Example: NEDT DiMarzio & McKnight, Northeastern University

  10. Thermal Detectors Photon Detectors Two Basic Detection Concepts i/P Absorber hn e- Heat Sink l Photon Energy: E=hn=hc/l Total Energy: Pt Photon Count: np=Pt/hn Electron Count: ne=hqPt/hn Electron Rate: ne/t=hqP/hn Current: ene/t=(hqe/hn)P Power: P Heating: (dT/dt)H = CP Cooling: k(dT/dt)C =(T-Ts) Steady State: (T-Ts)/kC = P DiMarzio & McKnight, Northeastern University Stopped Mon 5 Jan 04

  11. Thermal Characteristics Wide Bandwidth Accuracy Examples Thermocouple Thermopile Pyroelectric Photon Characteristics Speed Sensitivity Examples Photoemissive Photoconductive -intrinsic & extrinsic Photovoltaic - intrinsic & extrinsic Detector Types DiMarzio & McKnight, Northeastern University

  12. Course Overview (1) • 3 - Noise and Photon Detectors • - Materials Considertations • (4) in Photoemissive Detectors • (5,6) in Semiconductor Detectors • 7 - Types of Semiconductor Detectors • 8 - P-N Junction Effects & Other Detectors • 9,10 - Detectors as Circuit Elements DiMarzio & McKnight, Northeastern University

  13. Course Overview (2) • 11,12 - Coherent Detection • 13 - Semiconductor Photoconductive Detectors • 14 - Signals and Noise • 15 - Intro to Arrays & a bit about color • 16 - Gain & BW in Semiconductor Dets. • 17 - Array Detectors • 18 - Odds and Ends DiMarzio & McKnight, Northeastern University

  14. SNR Layout for Coherent Detection PLO Filter? Amp Preamp Ps BPF PBKG DiMarzio & McKnight, Northeastern University

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